Implement new gray mock.

chrome/browser/chromeos/login/background_view.cc

Index: chrome/browser/chromeos/login/background_view.cc
diff --git a/chrome/browser/chromeos/login/background_view.cc b/chrome/browser/chromeos/login/background_view.cc
index 6802b94dc1d040de0fd4bed767a936725ac686c5..249d9b0cb714534a2ffd6dbf20c601811e3f13d9 100644
--- a/chrome/browser/chromeos/login/background_view.cc
+++ b/chrome/browser/chromeos/login/background_view.cc
@@ -309,6 +309,10 @@ StatusAreaHost::ScreenMode BackgroundView::GetScreenMode() const {
   return kLoginMode;
 }
 
+StatusAreaHost::TextStyle BackgroundView::GetTextStyle() const {
+  return kWhitePlain;
+}
+
 // Overridden from LoginHtmlDialog::Delegate:
 void BackgroundView::OnLocaleChanged() {
   // Proxy settings dialog contains localized strings.